There are known several improvements in outlet boxes but generally a standard type box is used in most installations. Various improvements in electrical boxes are noted in the reference patents cited in U.S. Pat. No. 4,304,957.
In U.S. Pat. No. 4,304,957 (Slater et al) an electrical outlet box is disclosed having recessed wall areas that house panel mounting devices and electrical power cable entry ports. The cable entry ports of Slater have self-opening and self clamping closure panels extending angularly inward from the rim of the port which are also self-centering and self-adjusting for different cable sizes. In Slater as in all other type outlet boxes there are a maximum number of conductors permitted as per the National Electrical Code, NFPA 70. The National Fire Protection Association (NFPA) has released together with the National Electrical Code (NFPA70-1993) standards on the number conductors permitted to be used with specific size boxes.
In Article 370 of the National Electrical Code, a table 370-16(a) was presented indicating the maximum number of conductors for each size outlet box. This table is as follows:
__________________________________________________________________________ Min. Box Dimension, Inches Cu. In. Maximum Number of Conductors Trade Size or Type Cap. No. 18 No. 16 No. 14 No. 12 No. 10 No. 8 No. 6 __________________________________________________________________________ 4 .times. 11/4 Round or Octagonal 12.5 8 7 6 5 5 4 2 4 .times. 11/2 Round or Octagonal 15.5 10 8 7 6 6 5 3 4 .times. 21/8 Round or Octagonal 21.5 14 12 10 9 8 7 4 4 .times. 11/4 Square 18.0 12 10 9 8 7 6 3 4 .times. 11/2 Square 21.0 14 12 10 9 8 7 4 4 .times. 21/8 Square 30.3 20 17 15 13 12 10 6 411/16 .times. 11/4 Square 25.5 17 14 12 11 10 8 5 411/16 .times. 11/2 Square 29.5 19 16 14 13 11 9 5 411/16 .times. 21/8 Square 42.0 28 24 21 18 16 14 8 3 .times. 2 .times. 11/2 Device 7.5 5 4 3 3 3 2 1 3 .times. 2 .times. 2 Device 10.0 6 5 5 4 4 3 2 3 .times. 2 .times. 21/4 Device 10.5 7 6 5 4 4 3 2 3 .times. 2 .times. 21/2 Device 12.5 8 7 6 5 5 4 2 3 .times. 2 .times. 23/4 Device 14.0 9 8 7 6 5 4 2 3 .times. 2 .times. 31/2 Device 18.0 12 10 9 8 7 6 3 4 .times. 21/8 .times. 11/2 Device 10.3 6 5 5 4 4 3 2 4 .times. 21/8 .times. 17/8 Device 13.0 8 7 6 5 5 4 2 4 .times. 21/8 .times. 21/8 Device 14.5 9 8 7 6 5 4 2 33/4 .times. 2 .times. 21/2 Masonry 14.0 9 8 7 6 5 4 2 Box/Gang 33/4 .times. 2 .times. 31/2 Masonry 21.0 14 12 10 9 8 7 4 Box/Gang FS-Minimum Internal Depth 13.5 9 7 6 6 5 4 2 13/4 Single Cover/Gang FD-Minimum Internal Depth 18.0 12 10 9 8 7 6 3 23/8 Single Cover/Gang FS-Minimum Internal Depth 18.0 12 10 9 8 7 6 3 13/4 Multiple Cover/Gang FD-Minimum Internal Depth 24.0 16 13 12 10 9 8 4 23/8 Multiple Cover/Gang __________________________________________________________________________ For SI units: one cubic inch = 16.4 cm..sup.3
A number of older homes have interior walls that are studded sideways and in order to install a replacement outlet box in the wall one cuts a hole bigger than the replaceable box. When it is desired to use more conductors than previously used in the old box, a larger box must be installed. The large hole is then patched up after the installation of the new box. The normally used process, for example, when replacing a 2".times.3" box with a 4".times.4".times.11/2" box is to cut the dry wall then mount a 4".times.4".times.11/2" metal or plastic outlet box, then patch up the drywall or plaster opening. In some situations a larger outlet box cannot be installed because of the studs or other obstacles in the wall. If, for example, there are blocking pipes or sideway studdings installation of a box larger than the previously installed box poses several problems. While these obstructions can be relocated or removed, this would amount to substantial reconstruction and generally is not attempted. Therefore, there is a need for means to replace an old, smaller outlet box with a larger box that will permit a greater number of conductors to be placed therein.